Many approaches can be taken in the treatment of cancer. One approach is the use of radiosensitisers along with radiation therapy. This two-pronged approach increases the likelihood of success of the cancer therapy. Radiosensitisers are compounds which when administered to the patient make the tumour more sensitive to radiotherapy or act as an oxygen mimic such that they increase the free radicals available following the ionising radiation. The latter type of compound results in the repair mechanisms within the cell being overwhelmed and cell death occurring.
Radiosensitisers involve time-consuming administration by a specialist, which is expensive for the medical institution involved in the treatment. The radiosensitisers are generally given intravenously or by injection in large fluid volumes that take a significant amount of time to administer and a single dose may involve administration over more than one day. The invasive nature of the administration can lead to multiple puncture sites that are at risk of infection.
Most importantly, administration of the radiosensitiser is distressing to the patient. However, in order to maintain therapeutically effective levels within the tumours radiosensitisers that enhance sensitivity to radiation may be administered on a daily basis. Daily irradiation then takes place afterwards. Some cytotoxics that are used as radiosensitisers may be administered less frequently, generally once every 3-4 days or at least once per week (e.g. Cisplatin).
Compared to the administration of the radiosensitiser, irradiation is a relatively simple step. Irradiation often takes place for five days and then the patient has two days off before the cycle is repeated until the course of treatment devised by the patient's clinician is finished. The length of the course of treatment will depend, among other things, upon the patient, the type of cancer and the stage of cancer.
Examples of radiosensitisers for use in treating cancer include boron-containing compounds, and more particularly the carborane-containing nitroporphyrin compounds disclosed in WO 2008/133664.